This invention relates to glass halogen lamps and, in particular, to such lamps having reference features molded into the seal area thereof and contact pins attached to the lead wires and extending from the seal area.
In the prior art, baseless or all-glass lamps provided an economic alternative to based lamps for the automotive industry and others. The tungsten-halogen cycle was successfully applied to a broader range of lamps, improving the efficacy and lumen maintenance thereof. As described in U.S. Pat. No. 3,798,491, low cost miniature halogen lamps were realized through the substitution of a particular glass for quartz and the elimination of foliated lead wires.
Any advance in the art usually generates a new set of problems to be solved. As known by those of skill in the art, halogen cycle lamps require higher bulb wall temperatures than non-halogen cycle lamps. In particular, glass halogen lamps are characterized by high temperatures in the seal area during operation. In the past, these lamps have been based, e.g., with a ceramic pin base, to insulate the contact pins from the glass and to encapsulate the molybdenum lead wires to prevent oxidation thereof.
A pin base lamp, while affording good electrical contact, may not have adequate retention in the socket for vibration applications. In the past, wedge base lamps (non-halogen cycle) have been used in vibration applications. Contact is usually made to a wedge base lamp by socket spring terminals which press the lead wire against the seal area. Because of the high operating temperature in the seal area, wedge base glass halogen lamps may be subject to oxidized lead wires and poor electrical contact.